docs: def add_dnc(
          self,
          obj_id,
          channel='email',
          reason=MANUAL,
          channel_id=None,
          comments='via API'
      ):
          """
          Adds Do Not Contact
  
          :param obj_id: int
          :param channel: str
          :param reason: str
          :param channel_id: int
          :param comments: str
          :return: dict|str
          """
          data = {
              'reason': reason,
              'channelId': channel_id,
              'comments': comments
          }
          response = self._client.session.post(
              '{url}/{id}/dnc/add/{channel}'.format(
                  url=self.endpoint_url, id=obj_id, channel=channel
              ),
              data=data
          )
          return self.process_response(response)